Based on the IPCC report, the sign of the precipitation change due to aerosol is unknown. The objective of this study is to assess the climatic radiative effect of black carbon on tropical precipitation. An interactive aerosol-climate simulation by a global climate model with direct radiative effect of black carbon is diagnosed. The results are compared with long-term satellite data. Results indicate that there is a significant climate signal between black carbon and precipitation in the tropics. Such signals are different from model simulated washout effect. Areas with high black carbon concentrations exhibit both negative and positive correlations with precipitation depending on the area of focus. Consistency and discrepancy between model simulations and satellite observations are discussed.